1. Field of the Invention
The present invention relates to a printed circuit unit for a camera and particularly to a printed circuit unit having various functional elements (circuit paths or circuit chips) for exposure measuring, exposure operation and exposure value display, etc., mounted on a flexible printed circuit sheet.
2. Description of the Prior Art
Recently a camera employs more and more electronics technology, and it has become already general practice to conduct not only exposure measuring and operation of appropriate exposure based on the result of said measuring but also the control of exposure action thereof in an electric manner, and particularly nowadays for instance there is such system that a light emitting element such as LED (Light Emitting Diode) etc. is used so that exposure value can be digitally displayed in an electro-optical manner within a field of view finder. But in this kind of camera electric circuit devices which have become more and more large and complicated are built in the same in highly dense manner together with a number of electric circuit parts.
On the other hand, since a camera is a very equipment for which compactness in size and light weight are very valuable and important feature, various mechanical devices and optical assemblies which have already been made to have compact size are housed inside the housing thereof in a highly dense manner, thus only very small further scatteredly formed extra spaces are left for the above mentioned electric circuit systems, such as the space between an upper cover part of camera and mechanical parts or optical assemblies and the space between a bottom cover part of camera and mechanical parts. Therefore, in order to effectively utilize said very limited space, nowadays such efforts have been made to provide almost all of the above mentioned electric circuit systems in ICed (Integrated Circuited) manner as much as possible together with a vital core circuit part within the above mentioned limited space being scatteredly positioned except such electric parts as direct input and output interfaces for each of mechanical assemblies and optical assemblies, for example, various resistors to set film sensitivity, exposure time value or exposure aperture value, photo-sensing element, various switches, electro-magnet to control the action of shutter device or diaphragm device, and a display means to display exposure value, etc. In this case, further new and improved positional arrangement of each of said scatteredly positioned IC circuit parts and electric parts together with the form or arrangement of the electrical connections between said parts will be required.
Especially, as has been mentioned above, when the brightness of an object is measured by a photo-sensing element and the exposure value (the exposure time value or the exposure aperture value) to obtain appropriate exposure is operated based on the result of said measurement, further said exposure value (exposure time and/or aperture value) is optically displayed within a field of view finder by an electro-optical display element for example a light emitting element, a liquid crystal element, etc., since said photo-sensing element and display element are to constitute direct input and output interfaces for the optical assembly of camera, they need to be positioned closely facing to a part of the optical system of camera for example the view finder optical system. And in this case, the position at which each of said photo-sensing element and display element is placed will have limitations depending on the positional layout of the optical assembly of camera in view of the requirements for satisfying such conditions that the display information light beam from the display element must not impinge on the photo-sensing element to impair the photo-sensing accuracy, and the photo-sensing element must be able to measure object brightness accurately, further the display information by the display element must be visually recognized within the field of view finder without any difficulties, etc.
On the other hand, an exposure operation circuit to determine appropriate exposure value based on the photo-sensing output from the photo-sensing element, even if they are formed by IC into one or more IC chips, is ordinarily mounted for example using the space between a camera bottom cover and mechanical part or the space between a camera upper cover and a penta-prism constituting the view finder optical system of camera, from the view point of convenience for adjustment thereof and for built-in operation thereof into a camera, therefore, there is a problem for wiring for electrical connection between the exposure operation circuit and the photo-sensing element and display element. If thus scatteredly positioned IC circuit parts and each of electric parts are connected by conventional lead wires, especially its wiring operation becomes very complicated and assembly work of camera becomes very difficult, further such fear as an increase in troubles by damage on the lead wire or failure in connection, etc. is generated, further there will be such disadvantages that the positional layout of various mechanical assemblies and optical assemblies of camera will be greatly influenced by said complication, difficulty and fear. Thus a further improved set up and positional arrangement for electric circuit systems are strongly desired to satisfactorily eliminate these disadvantages.